1.) Field of the Invention
The present invention relates generally to an infrared radiation detector. In particular, it relates to a detector, incorporated with a stacked-up multifaceted arc lens assembly and a deflector plate, with a detecting range beyond 120 degrees, as well as a method of extending the detecting range.
2.) Description of the Prior Art
Generally, an infrared radiation detector is used in a security system, a temperature sensing system, a dimmer control system, and other automatic monitoring and control systems. For example, in a security system, an infrared radiation detector is employed in a high rise building monitoring and control arrangement to detect the infrared ray emitted by an intruder or intruders, thereby actuating an alarm circuit or performing other relevant functions.
A common detecting range for prior art infrared radiation detectors is approximately from 110 degrees to 120 degrees, giving rise to a detection blind zone beyond 120 degrees. A prior art infrared radiation detector is normally wall- or eave- or ceiling-mounted. In that connection, there will be a detection blind zone, especially at wall corners or extremities. This blind zone is enlarged in proportion to the increase in surveillance spacing. To cope with this blind zone problem, several proposals had been taught. Nally Chang disclosed in U.S. Pat. No. 5,103,346 a detecting range of larger than 120 degrees with the assistance of right and left deflector surfaces provide on each side of signal deflector plate in front of a signal-receiving detector. FIG. 1 illustrates a schematic view of the detecting range according to Chang""s case. Upon further investigation, it was found that the above-mentioned detector was not responsive between 70 degrees to 80 degrees from the central axis of a signal-receiving detector, resulting in a detection blind zone at A1 region.
Other relevant prior art cases include U.S. Pat. No. 3,923,382 (Harding), U.S. Pat. No. 4,268,752 (Herwig), U.S. Pat. No. 4,644,147 (Zublin), U.S. Pat. No. 4,703,171 (Kahl et al).
A primary object of the present invention is to overcome the above detection blind zone of the prior art detectors.
Accordingly, the present invention discloses an incorporation of a stacked-up multifaceted arc lens assembly and a deflector plate to an infrared radiation detector. In a preferred embodiment of the invention, at least two reflection planes are integrally provided on each side of a signal deflector plate, and a stacked-up arc lens assembly has two stacked up broad lenses at either side of a central focusing zone to gather and focus more incident infrared rays from a wider detection range.
The invention will be described further in one preferred embodiment of the invention, by way of example, with reference to the drawings appended below.